This application claims the priority of Japanese Patent Application No. 4-280469 filed Sep. 25, 1992, which is incorporated herein by reference.
2. Field of the invention
The present invention relates to a nonaqueous secondary battery comprising an oxide of manganese as an active material of a positive electrode and, more particularly, to improvement of this active material in order to improve the charge-discharge cycle characteristics.
2. Description of the prior art
Manganese oxides of the general formula Li.sub.1-x Mn.sub.2 O.sub.4 (0.ltoreq.X.ltoreq.1), typically LiMn.sub.2 O.sub.4, have been used as active materials of positive electrodes of nonaqueous secondary batteries, because these oxides permit high voltage to be taken out.
However, with the above manganese oxides, manganese dissolves out during charge when the positive electrode has high potential, and hence there has been a problem that positive electrodes containing such manganese oxides markedly decrease their discharge capacity at an initial period of charge-discharge cycle.